Supercritical water process to produce bottom free hydrocarbons

ABSTRACT

A process to produce a light hydrocarbon fraction from a heavy residue feed, the process comprising the steps of operating the first supercritical reactor such that the heavy residue feed and the supercritical water stream undergo conversion reactions to produce a reactor effluent, introducing the reactor effluent to a top inlet in a top portion of a second supercritical reactor, introducing a supercritical water stream to a bottom inlet in a bottom portion of the second supercritical reactor, operating the second supercritical reactor such that the bottom of the barrel fraction is configured to settle in the bottom portion of the second supercritical reactor, withdrawing an upgraded product stream from a top outlet in the top portion of the second supercritical reactor, and withdrawing a heavy product stream from a bottom outlet in the bottom portion of the second supercritical reactor.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of and claims priority fromU.S. Non-Provisional patent application Ser. No. 16/442,189 filed onJun. 14, 2019. For purposes of United States patent practice, thisapplication incorporates the contents of the Non-Provisional Applicationby reference in its entirety.

TECHNICAL FIELD

Disclosed are methods for upgrading petroleum. Specifically, disclosedare methods and systems for upgrading petroleum to produce a bottom-freehydrocarbon stream.

BACKGROUND

One of the biggest challenges of refining crude oil is the heaviestfraction, also known as the “bottom of the barrel.” Upgrading the bottomof the barrel to produce valuable fuel and chemicals is difficult due toits composition and boiling point. The bottom of the barrel, which oftenis equivalent to the vacuum residue fraction, has a boiling point ofgreater than 1050 deg F. (565 deg C.). The bottom of the barrel caninclude concentrated amounts of asphaltenes, metallic compounds, such asnickel and vanadium, sulfur, nitrogen, and oxygen. These compounds canbe present in greater concentrations than in other fractions of thecrude oil.

Refining these compounds is difficult for several reasons. Processingfractions with high concentrations of asphaltenes can result in theprecipitation of those fractions to form coke or sludge. Highconcentrations of heteroatoms, particularly metallic compounds can causesever and rapid deactivation of catalysts. Finally, the greatermolecular weights and complicated molecular structures of the compoundsfound in the bottom of the barrel can hinder access to catalyst, due tosteric hindrance, limiting conversion of those compounds. As a result,the bottom of the barrel fraction is the least utilized and lowestvalued fraction of crude oil.

One process to treat the bottom of the barrel fraction ishydroprocessing. Hydroprocessing converts heavy compounds to lighthydrocarbons in the presence of a catalyst and external supply ofhydrogen. Hydroprocessing requires access to large amounts of hydrogen.Additionally, because of the concentrated amount of inhibitors, such asasphaltene, converting the bottom of the barrel fraction requireshydrogen pressures greater than 100 bar and often closer to 150 bar andtemperatures greater than 400 deg C. Compressing hydrogen to theseconditions requires significant amounts of energy and the materials ofconstruction must be special alloys to maintain mechanical integrityunder such a high hydrogen partial pressure environment. Even underoptimal conditions, hydroprocessing units tend to be limited to about 60percent by weight (wt %) conversion of bottom of barrel fraction tolighter hydrocarbons.

Another process used to treat the bottom of the barrel fraction isthermal cracking, where the major reaction is the breaking ofcarbon-carbon bonds. In thermal cracking operations, such as a cokingprocess, lighter hydrocarbons can be produced from the bottom of thebarrel fraction, but an amount of the carbon in the fraction is alsoconverted to solid coke.

Another process used to treat the bottom of the barrel fraction is tofirst separate the bottom of the barrel fraction or a portion of thebottom of the barrel fraction. Separation methods can includedistillation and solvent deasphalting. Distillation is the most commonprocess. Solvent deasphalting can be used to separate an asphaltenefraction containing asphaltenes and a concentrated amount ofheteroatoms. However, separation process do not of themselves upgradethe heavy compounds in the bottom of the barrel fraction and thus, mustbe employed with another process to upgrade the heavy compounds.

SUMMARY

Disclosed are methods for upgrading petroleum. Specifically, disclosedare integrated methods and systems for upgrading petroleum to produce abottom-free hydrocarbon stream.

In a first aspect, a process to produce a light hydrocarbon fractionfrom a heavy residue feed is provided. The process includes the steps ofintroducing the heavy residue feed to a first supercritical reactor,introducing a supercritical water feed to the first supercriticalreactor, operating the first supercritical reactor such that the heavyresidue feed and the supercritical water stream undergo conversionreactions to produce a reactor effluent, where the temperature in thefirst supercritical water is between 380 deg C. and 450 deg, where thepressure in the first supercritical water is greater than the criticalpressure of water, where the reactor effluent includes a lighthydrocarbon fraction, a bottom of the barrel fraction, and water. Theprocess further includes the steps of introducing the reactor effluentto a top inlet in a top portion of a second supercritical reactor thatincludes a vertical reactor, introducing a supercritical water stream toa bottom inlet in a bottom portion of the second supercritical reactor,where the supercritical water stream includes supercritical water, wherethe temperature of the supercritical water stream is between thecritical temperature of water and 10 deg C. less than the temperature ofthe reactor effluent from the first supercritical reactor, and operatingthe second supercritical reactor such that the bottom of the barrelfraction is operable to settle in the bottom portion of the secondsupercritical reactor, where the supercritical water in thesupercritical water stream is operable to extract the light hydrocarbonfraction from the reactor effluent. The process further includes thesteps of withdrawing an upgraded product stream from a top outlet in thetop portion of the second supercritical reactor, where the upgradedproduct stream includes the light hydrocarbon fraction, and withdrawinga heavy product stream from a bottom outlet in the bottom portion of thesecond supercritical reactor, where the heavy product stream includesthe bottom of the barrel fraction.

In certain aspects, the process further includes the steps of increasinga pressure of a residue feed in a hydrocarbon pump to produce apressurized residue feed, where the pressure of the pressurized residuefeed is greater than the critical pressure of water, introducing thepressurized residue feed to a hydrocarbon exchanger, increasing atemperature of the pressurized residue feed in the hydrocarbon exchangerto produce the heavy residue feed, increasing a pressure of a water feedin a water pump to produce a pressurized water feed, where the pressureof the pressurized water feed is greater than the critical pressure ofwater, introducing the pressurized water feed to a water exchanger,increasing a temperature of the pressurized water feed in the waterexchanger to produce the supercritical water feed, increasing a pressureof a water stream in a liquid pump to produce a pressurized waterstream, where the pressure of the pressurized water stream is greaterthan the critical pressure of water, introducing the pressurized waterstream to a water heater, and increasing a temperature of thepressurized water stream in the water heater to produce thesupercritical water stream. In certain aspects, the process furtherincludes the steps of introducing the heavy residue feed to a mixer,introducing the supercritical water feed to the mixer, mixing the heavyresidue feed and the supercritical water feed to produce a mixed feed,where a ratio of the volumetric flow rate of the supercritical waterfeed to the volumetric flow rate of the heavy residue feed is between10:1 and 1:4 at standard ambient temperature and pressure (SATP), andintroducing the mixed feed to the first supercritical reactor. Incertain aspects, the upgraded product stream includes less than 10 wt %bottom of the barrel fraction. In certain aspects, a ratio of thevolumetric flow rate of the supercritical water stream to the combinedvolumetric flow rate of heavy residue feed and supercritical water feedis between 5:1 and 1:10 at standard atmospheric temperature and pressure(SATP). In certain aspects, a residence time in the first supercriticalreactor is between 1.2 minutes and 60 minutes. In certain aspects, aratio of a total flow rate at SATP in second supercritical reactor to areactor volume of second supercritical reactor is between 1 per hour and6 per hour. In certain aspects, the heavy residue feed is selected fromthe group consisting of an atmospheric residue, a vacuum gas oil, and avacuum residue. In certain aspects, the bottom portion includes thesection of a cylindrical body of the supercritical reactor defining 10%of the total length measured from a lowest elevation of the cylindricalbody of the second supercritical reactor. In certain aspects, the topportion includes the section of a cylindrical body of the supercriticalreactor defining 10% of the total length measured from a highestelevation of the cylindrical body of the second supercritical reactor.

In a second aspect, a system to produce a light hydrocarbon fractionfrom a heavy residue feed is provided. The system includes a firstsupercritical reactor configured to operate such that the heavy residuefeed and a supercritical water feed undergo conversion reactions toproduce a reactor effluent, where the temperature in the firstsupercritical water is between 380 deg C. and 450 deg, where thepressure in the first supercritical water is greater than the criticalpressure of water, where the reactor effluent includes a lighthydrocarbon fraction, a bottom of the barrel fraction, and water, a topinlet in a top portion of a second supercritical reactor fluidlyconnected to the first supercritical reactor, the top inlet configuredto receive the reactor effluent, where the second supercritical reactorincludes a vertical reactor, a bottom inlet in a bottom portion of thesecond supercritical reactor, the bottom inlet configured to receive asupercritical water stream, where the supercritical water streamincludes supercritical water, where the temperature of the supercriticalwater stream is between the critical temperature of water and 10 deg C.less than the temperature of reactor effluent, the second supercriticalreactor configured to operate such that the bottom of the barrelfraction is configured to settle in the bottom portion of the secondsupercritical reactor, where the supercritical water in thesupercritical water stream is operable to extract the light hydrocarbonfraction from the reactor effluent, a top outlet fluidly connected tothe top portion of the second supercritical reactor, the top outletconfigured to receive an upgraded product stream, where the upgradedproduct stream includes the light hydrocarbon fraction, and a bottomoutlet in the bottom portion of the second supercritical reactor, thebottom outlet configured to receive a heavy product stream that includesthe bottom of the barrel fraction.

In certain aspects, the system further includes a hydrocarbon pumpconfigured to increase a pressure of a residue feed to produce apressurized residue feed, where the pressure of the pressurized residuefeed is greater than the critical pressure of water, a hydrocarbonexchanger fluidly connected to the hydrocarbon pump configured toincrease a temperature of the pressurized residue feed in thehydrocarbon exchanger to produce the heavy residue feed, a water pumpconfigured to increase a pressure of a water feed to produce apressurized water feed, where the pressure of the pressurized water feedis greater than the critical pressure of water, a water exchangerfluidly connected to the water pump configured to increase a temperatureof the pressurized water feed in the water exchanger to produce thesupercritical water feed, a liquid pump configured to increase apressure of a water stream to produce a pressurized water stream, wherethe pressure of the pressurized water stream is greater than thecritical pressure of water, and a water heater fluidly connected to theliquid pump, the water heater configured to increase a temperature ofthe pressurized water stream to produce the supercritical water stream.In certain aspects, the system further includes the steps of a mixerfluidly connected to the hydrocarbon exchanger and the water exchanger,the mixer configured to mix the heavy residue feed and the supercriticalwater feed to produce a mixed feed, where a ratio of the volumetric flowrate of the supercritical water feed to the volumetric flow rate of theheavy residue feed is between 10:1 and 1:4 at standard ambienttemperature and pressure (SATP).

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the scope willbecome better understood with regard to the following descriptions,claims, and accompanying drawings. It is to be noted, however, that thedrawings illustrate only several embodiments and are therefore not to beconsidered limiting of the scope as it can admit to other equallyeffective embodiments.

FIG. 1 provides a process diagram of an embodiment of the process.

FIG. 2 provides a process diagram of an embodiment of the process.

In the accompanying Figures, similar components or features, or both,may have a similar reference label.

DETAILED DESCRIPTION

While the scope of the apparatus and method will be described withseveral embodiments, it is understood that one of ordinary skill in therelevant art will appreciate that many examples, variations andalterations to the apparatus and methods described here are within thescope and spirit of the embodiments.

Accordingly, the embodiments described are set forth without any loss ofgenerality, and without imposing limitations, on the embodiments. Thoseof skill in the art understand that the scope includes all possiblecombinations and uses of particular features described in thespecification.

Described here are processes and systems for upgrading a bottom of thebarrel fraction to produce a light hydrocarbon fraction that isbottom-free.

Advantageously, the process for upgrading a bottom of the barrelfraction can produce a bottom-free hydrocarbon stream from a heavyresidue feed using supercritical water. Advantageously, the process forupgrading a bottom of the barrel fraction enables upgrading andseparation in the one step of the process. Advantageously, thebottom-free hydrocarbon stream can contain a minimal amount of thebottom of the barrel fraction. Advantageously, the bottom-freehydrocarbon stream can be used in other fractions requiring a minimalamount of the bottom of the barrel fraction, such as hydroprocessing, acoking process, a gasification process, and power generation.Advantageously, the use of a second supercritical reactor as anextractor with supercritical water acting as a solvent can contribute tothe separation of the light hydrocarbon fraction from the bottom of thebarrel fraction. Advantageously, this separation function aids inproduction of a bottom-free hydrocarbon fraction. Advantageously, theaddition of the second supercritical reactor avoids the installation ofa separation unit or separation process to remove the bottom of thebarrel fraction from the upgraded hydrocarbons. Advantageously, theprocess for upgrading a bottom of the barrel fraction combines upgradingand extraction in a single supercritical water process.

As used throughout, “external supply of hydrogen” refers to the additionof hydrogen to the feed to the reactor or to the reactor itself. Forexample, a reactor in the absence of an external supply of hydrogenmeans that the feed to the reactor and the reactor are in the absence ofadded hydrogen gas (H₂) or liquid, such that no hydrogen (in the formH₂) is a feed or a part of a feed to the reactor.

As used throughout, “external supply of catalyst” refers to the additionof catalyst to the feed to the reactor or the presence of a catalyst inthe reactor, such as a fixed bed catalyst in the reactor. For example, areactor in the absence of an external supply of catalyst means nocatalyst has been added to the feed to the reactor and the reactor doesnot contain a catalyst bed in the reactor.

As used throughout, “atmospheric residue” or “atmospheric residuefraction” refers to the fraction of oil-containing streams having a T5%cut point of 600 deg F., such that 95 wt % of the hydrocarbons haveboiling points greater than 600 deg F., and alternately a T5% cut pointof 650 deg F., such that 95 wt % of the hydrocarbons have boiling pointsgreater than 650 deg F. The atmospheric residue includes the vacuumresidue fraction. Atmospheric residue can refer to the composition of anentire stream, such as when the feedstock is from an atmosphericdistillation unit, or can refer to a fraction of a stream, such as whena whole range crude is used.

As used throughout, “bottom of the barrel” or “bottom of the barrelfraction” or “vacuum residue” or “vacuum residue fraction” refers to thefraction of oil-containing streams having a T10% cut point of greaterthan 900 deg F., such that 90 wt % of the hydrocarbons have boilingpoints greater than 900 deg F., and alternately, a T10% cut point ofgreater than 1050 deg F., such that 90 wt % of the hydrocarbons haveboiling points greater than 1050 deg F. Vacuum residue can refer to thecomposition of an entire stream, such as when the feedstock is from avacuum distillation unit or can refer to a fraction of stream, such aswhen a whole range crude is used.

As used throughout, “T10% cut point” refers to the True Boiling Point(TBP) at which 10% of the volume of oil can be recovered. Cut pointsrefer to the temperature that represents the limits of a distillatefraction.

As used throughout, “T95% cut point” refers to the True Boiling Point(TBP) at which 95% of the volume of oil can be recovered. Cut pointsrefer to the temperature that represents the limits of a distillatefraction.

As used throughout, “asphaltene” refers to the fraction of anoil-containing stream, which is not soluble in a n-alkane, such asn-pentane or more particularly, n-heptane.

As used throughout, “heavy fraction” refers to the fraction in thepetroleum feed having a true boiling point (TBP) 10% that is equal to orgreater than 650 deg F. (343 deg C.), and alternately equal to orgreater than 1050 deg F. (566 deg C.). Examples of a heavy fraction caninclude the atmospheric residue fraction or vacuum residue fraction. Theheavy fraction can include components from the petroleum feed that werenot converted in the supercritical water reactor. The heavy fraction canalso include hydrocarbons that were dimerized or oligomerized in thesupercritical water reactor due to either lack of hydrogenation orresistance to thermal cracking.

As used throughout, “light hydrocarbon fraction” refers to the fractionin the petroleum feed that is not considered the heavy fraction. Forexample, when the heavy fraction refers to the fraction having a TBP 10%that is equal to or greater than 650 deg F. the light hydrocarbonfraction has a TBP 90% that is less than 650 deg F. For example, whenthe heavy fraction refers to the fraction having a TBP 10% equal to orgreater than 1050 deg F. the light hydrocarbon fraction has a TBP 90%that is less than 1050 deg F.

As used throughout, “coke” refers to the toluene insoluble materialpresent in petroleum.

As used throughout, “bottom-free hydrocarbon stream” refers to a streamthat contains less than 10 wt % heavy fraction, alternately less than 8wt % heavy fraction, alternately less than 5 wt % heavy fraction, andalternately less than 1 wt % heavy fraction.

As used throughout, “cracking” refers to the breaking of hydrocarbonsinto smaller ones containing fewer carbon atoms due to the breaking ofcarbon-carbon bonds.

As used throughout, “upgrade” means one or all of increasing APIgravity, decreasing the amount of impurities, such as sulfur, nitrogen,and metals, decreasing the amount of asphaltene, and increasing theamount of the light hydrocarbon fraction in a process outlet streamrelative to the process feed stream. One of skill in the art understandsthat upgrade can have a relative meaning such that a stream can beupgraded in comparison to another stream, but can still containundesirable components such as impurities.

As used here, “conversion reactions” refers to reactions that canupgrade a hydrocarbon stream including cracking, isomerization,alkylation, dimerization, aromatization, cyclization, desulfurization,denitrogenation, deasphalting, and demetallization.

The following embodiments, provided with reference to the figures,describe the upgrading process.

Referring to FIG. 1, a process flow diagram of an upgrading process isprovided. Heavy residue feed 10 is introduced to first supercriticalreactor 100 along with supercritical water feed 15. Heavy residue feed10 can be any petroleum feedstock containing a bottom of the barrelfraction. The petroleum feedstock can be any hydrocarbon source derivedfrom petroleum, coal, coal liquid, or biomaterials. Heavy residue feed10 can include whole range crude oil, distilled crude oil, residue oil,topped crude oil, product stream from oil refineries, product streamsfrom steam cracking processes, liquefied coals, liquid productsrecovered from oil or tar sands, bitumen, oil shale, asphaltene, andbiomass hydrocarbons. Residue oils can include atmospheric residue,vacuum gas oil, and bottom of the barrel fraction. In at least oneembodiment, heavy residue feed 10 is selected from atmospheric residue,vacuum gas oil, and vacuum residue. Heavy residue feed 10 can be at apressure between 22.064 MPa and 30 MPa and can be at a temperaturebetween ambient temperature and 250 deg C. Temperature should bemaintained at or less than 250 deg C. to reduce or eliminate theformation of coke in the process units and piping upstream of firstsupercritical reactor 100.

Supercritical water feed 15 can be any demineralized water having aconductivity less than 1.0 microSiemens per centimeter (μS/cm),alternately less 0.5 μS/cm, and alternately less than 0.1 μS/cm. In atleast one embodiment, supercritical water feed 15 is demineralized waterhaving a conductivity less than 0.1 μS/cm. Supercritical water feed 15can have a sodium content of less than 5 micrograms per liter (μg/L) andalternately less than 1 μg/L. Supercritical water feed 15 can have achloride content of less than 5 μg/L and alternately less than 1 μg/L.Supercritical water feed 15 can have a silica content of less than 3μg/L. Supercritical water feed 15 can be at a pressure between 22.064MPa and 30 MPa. The temperature of supercritical water feed 15 can begreater than the supercritical temperature of water, alternately at atemperature between 374 deg C. and 600 deg C., and alternately between400 deg C. and 550 deg C. Maintaining the temperature of supercriticalwater feed 15 at less than 600 deg C. avoids the use of special hightemperature alloys in piping and connections within the system.

The ratio of the volumetric flow rate of supercritical water feed 15 toheavy residue feed 10 can be between 10:1 and 1:4 at standard ambienttemperature and pressure (SATP), alternately between 3:1 and 1:2 atSATP, and alternately between 2:1 to 1:1 at SATP.

In an embodiment of the upgrading process, heavy residue feed 10 andsupercritical water feed 15 can be mixed upstream of first supercriticalreactor 100 and introduced to first supercritical reactor 100 as a mixedstream.

Referring to FIG. 2, an embodiment of the upgrading process is providedwith reference to FIG. 1. Residue feed 50 can be introduced tohydrocarbon pump 300. Residue feed 50 can be any petroleum feedstockcontaining a bottom of the barrel fraction. The petroleum feedstock canbe any hydrocarbon source derived from petroleum, coal, coal liquid, orbiomaterials. Residue feed 50 can include whole range crude oil,distilled crude oil, residue oil, topped crude oil, product stream fromoil refineries, product streams from steam cracking processes, liquefiedcoals, liquid products recovered from oil or tar sands, bitumen, oilshale, asphaltene, and biomass hydrocarbons. Residue oils can includeatmospheric residue, vacuum gas oil, and vacuum residue. In at least oneembodiment, residue feed 50 is selected from atmospheric residue, vacuumgas oil, and vacuum residue. In at least one embodiment, residue feed 50can be at ambient pressure and can be at a temperature to ensure thepetroleum feedstock flows.

Hydrocarbon pump 300 can be any type of pump capable of increasing thepressure of residue feed 50 to greater than the critical pressure ofwater. Examples of pumps suitable for use as hydrocarbon pump 300 caninclude metering pumps, plunger pumps, or any other pumps known in theart. The pressure of residue feed 50 can be increased in hydrocarbonpump 300 to produce pressurized residue feed 60. The pressure ofpressurized residue feed 60 can be greater than the critical pressure ofwater and alternately between 22.064 MPa and 30 MPa. Pressurized residuefeed 60 can be introduced to hydrocarbon exchanger 350.

Hydrocarbon exchanger 350 can be any type of heat exchanger capable ofincreasing the temperature of pressurized residue feed 60. Examples ofhydrocarbon exchanger 350 can include a heat exchanger, an electricheater, and a fired heater. The temperature of pressurized residue feed60 can be increased in hydrocarbon exchanger 350 to produce heavyresidue feed 10. The temperature of heavy residue feed 10 can depend onthe viscosity of residue feed 50. For viscous feeds, the temperatureshould be sufficient to enable residue feed 50 to flow.

Water feed 55 can be introduced to water pump 400. Water feed 55 can beany demineralized water having a conductivity less than 1.0 microSiemensper centimeter (μS/cm), alternately less 0.5 μS/cm, and alternately lessthan 0.1 μS/cm. In at least one embodiment, water feed 55 isdemineralized water having a conductivity less than 0.1 μS/cm. Waterfeed 55 can have a sodium content of less than 5 micrograms per liter(μg/L) and alternately less than 1 μg/L. Water feed 55 can have achloride content of less than 5 μg/L and alternately less than 1 μg/L.Water feed 55 can have a silica content of less than 3 μg/L. In at leastone embodiment, water feed 55 can be at ambient temperature and apressure between 5 psig and 100 psig such that dissolved gases can beremoved.

Water pump 400 can be any type of pump capable of increasing thepressure of water feed 55 to greater than the critical pressure ofwater. Examples of pumps suitable for use as water pump 400 can includemetering pumps, plunger pumps, or any other pumps known in the art. Thepressure of water feed 55 can be increased in water pump 400 to producepressurized water feed 65. The pressure of pressurized water feed 65 canbe greater than the critical pressure of water and alternately between22.064 Megapascals (MPa) and 30 MPa. Pressurized water feed 65 can beintroduced to water exchanger 450.

Water exchanger 450 can be any type of heat exchanger capable ofincreasing the temperature of pressurized water feed 65 to greater thanthe critical temperature of water. Examples of water exchanger 450 caninclude a heat exchanger, an electric heater, and a fired heater. Thetemperature of pressurized water feed 65 can be increased in waterexchanger 450 to produce supercritical water feed 15.

Heavy residue feed 10 and supercritical water feed 15 can be introducedto mixer 500 to produce mixed feed 70. Mixer 500 can be any type ofmixing device capable of mixing a petroleum feedstock and asupercritical water stream. Examples of mixing devices suitable for useas mixer 500 can include a static mixer, an inline mixer, animpeller-embedded mixer, a CSTR-type mixer, and other mixers. The ratioof the volumetric flow rate of supercritical water feed 15 to heavyresidue feed 10 introduced to mixer 500 can be between 10:1 and 1:4 atstandard ambient temperature and pressure (SATP), alternately between3:1 and 1:2 at SATP, and alternately between 2:1 to 1:1 at SATP. Thepressure of mixed feed 70 can be between 22.064 MPa and 30 MPa. Thetemperature of mixed feed 70 can depend on the temperature of heavyresidue feed 10 and supercritical water feed 15. The temperature ofmixed feed 70 can be greater than 360 deg C., alternately between 360deg C. and 500 deg C., alternately between 380 deg C. and 450 deg C. Thetemperature in mixed feed 70 can be tuned by adjusting the temperatureof heavy residue feed 10, supercritical water feed 15, and adjustingboth heavy residue feed 10 and supercritical water feed 15. In at leastone embodiment, a temperature sensor can be placed at the outlet ofmixer 500. The temperature sensor can provide data on the temperature ofmixed feed 70 as part of a control loop to tune the temperature in mixedfeed 70.

Returning to FIG. 1, first supercritical reactor 100 can be any type ofreactor capable of operating under supercritical conditions and allowingconversion reactions. In at least one embodiment, first supercriticalreactor 100 can include more than one physical unit. Examples ofreactors suitable for use in first supercritical reactor 100 can includetubular-type, vessel-type, CSTR-type, and combinations of the same.First supercritical reactor 100 can include an upflow reactor, adownflow reactor, and a combination of at least one upflow reactor andat least one downflow reactor. First supercritical reactor 100 caninclude a vertical reactor, a horizontal reactor, or mixed verticalreactor and horizontal reactor. First supercritical reactor 100 can havea reactor volume such that the ratio of total flow rate at SATP toreactor volume is between 0.5 per hour and 4.5 per hour and alternatelybetween 1.2 per hour and 3.2 per hour. The total flow rate is the sum ofthe flow rate of heavy residue feed 10 and supercritical water feed 15.The residence time in first supercritical reactor 100 can be in therange between 1.2 minutes (min) and 60 min and alternately between 2 minand 27 min. The residence time in first supercritical reactor 100 iscalculated by assuming the internal fluid has the same density as waterat the conditions in first supercritical reactor 100. The temperature infirst supercritical reactor 100 can be maintained at a temperaturebetween 380 deg C. and 450 deg C. and alternately between 405 deg C. and450 deg C. The temperature in first supercritical reactor 100 is notisothermal. First supercritical reactor 100 can include a heater tomaintain the temperature. The heater can be an internal heater, anexternal heater, and combinations of the same. Examples of suitableheaters can include an electric heater, a fired heater, a heat exchangerand combinations of the same. The pressure in first supercriticalreactor 100 can be maintained at a pressure between 22.074 MPa and 30MPa. First supercritical reactor 100 is in the absence of an externalsupply of catalyst. In at least one embodiment, first supercriticalreactor 100 can be in the absence of an external supply of hydrogen.Heavy residue feed 10 and supercritical water feed 15 undergo conversionreactions in first supercritical reactor 100 to produce reactor effluent20.

Thermal cracking of hydrocarbons in supercritical water is differentfrom conventional thermal processes such as coking and hydroprocessing.Hydrocarbon reactions in supercritical water upgrade heavy oil and crudeoil containing sulfur compounds to produce products that have lighterfractions. Supercritical water has unique properties making it suitablefor use as a petroleum reaction medium where the reaction objectives caninclude conversion reactions, desulfurization reactions denitrogenationreactions, and demetallization reactions. Supercritical water is waterat a temperature at or greater than the critical temperature of waterand at a pressure at or greater than the critical pressure of water. Thecritical temperature of water is 373.946 ° C. The critical pressure ofwater is 22.06 megapascals (MPa). Advantageously, the dielectricconstant of supercritical water enables hydrocarbons to be dissolved init. Advantageously, at supercritical conditions water acts as both ahydrogen source and a solvent (diluent) in conversion reactions,desulfurization reactions and demetallization reactions and a catalystis not needed. Hydrogen from the water molecules is transferred to thehydrocarbons through direct transfer or through indirect transfer, suchas the water gas shift reaction.

Without being bound to a particular theory, it is understood that thebasic reaction mechanism of supercritical water mediated petroleumprocesses is the same as a free radical reaction mechanism. Radicalreactions include initiation, propagation, and termination steps. Withhydrocarbons, especially heavy molecules such as C10+, initiation is themost difficult step. Initiation requires the breaking of chemical bonds.The bond energy of carbon-carbon bonds is about 350 kJ/mol, while thebond energy of carbon-hydrogen is about 420 kJ/mol. Due to the chemicalbond energies, carbon-carbon bonds and carbon-hydrogen bonds do notbreak easily at the temperatures in a supercritical water process, 380deg C. to 450 deg C., without catalyst or radical initiators. Incontrast, carbon-sulfur bonds cover a range of bond energies that areeach lower than the bond energies of carbon-carbon bonds andcarbon-hydrogen bonds.

Thermal energy creates radicals through chemical bond breakage.Supercritical water creates a “cage effect” by surrounding the radicals.The radicals surrounded by water molecules cannot react easily with eachother, and thus, intermolecular reactions that contribute to cokeformation are suppressed. The cage effect suppresses coke formation bylimiting inter-radical reactions. Supercritical water, having lowdielectric constant, dissolves hydrocarbons and surrounds radicals toprevent the inter-radical reaction, which is the termination reactionresulting in condensation (dimerization or polymerization). Because ofthe barrier set by the supercritical water cage, hydrocarbon radicaltransfer is more difficult in supercritical water as compared tocompared to conventional thermal cracking processes, such as delayedcoker, where radicals travel freely without such barriers.

In at least one embodiment, the temperature of reactor effluent 20 canbe monitored with a temperature sensor at the outlet of firstsupercritical reactor 100. The temperature of reactor effluent 20 can bemonitored as part of the process control scheme of the system.Monitoring the temperature of reactor effluent 20 can be used to controlthe power used by the heaters for first supercritical reactor 100.

Reactor effluent 20 can contain a light hydrocarbon fraction, a bottomof the barrel fraction, and water. Reactor effluent 20 can containupgraded hydrocarbons as compared to heavy residue feed 10. Reactoreffluent 20 can be a well-mixed stream, such that the hydrocarbons aredispersed in the supercritical water creating a more homogeneous streamthan when the supercritical water and hydrocarbons are first in contact.Reactor effluent 20 can contain part of the light hydrocarbon fractionmixed in supercritical water and can include part of the lighthydrocarbon fraction mixed in the bottom of the barrel fraction.

Reactor effluent 20 is introduced to top inlet 205 of secondsupercritical reactor 200. Supercritical water stream 25 is introducedto bottom inlet 215 of second supercritical reactor 200.

Supercritical water stream 25 can be any demineralized water having aconductivity less than 1.0 microSiemens per centimeter (μS/cm),alternately less 0.5 μS/cm, and alternately less than 0.1 μS/cm. In atleast one embodiment, supercritical water stream 25 is demineralizedwater having a conductivity less than 0.1 μS/cm. Supercritical waterstream 25 can have a sodium content of less than 5 micrograms per liter(μg/L) and alternately less than 1 μg/L. Supercritical water stream 25can have a chloride content of less than 5 μg/L and alternately lessthan 1 μg/L. Supercritical water stream 25 can have a silica content ofless than 3 μg/L. Supercritical water stream 25 can be at a temperaturegreater than the critical temperature of water, alternately at atemperature between the critical temperature of water and 10 degreesless than the temperature of reactor effluent 20, and alternately at atemperature between 10 degrees and 50 degrees less than the temperatureof reactor effluent 20. For example, if the temperature of reactoreffluent 20 is at 450 deg C., then the temperature of supercriticalwater stream 25 is between 400 deg C. and 440 deg C. and alternately ifthe temperature of reactor effluent 20 is at 380 deg C., then thetemperature of supercritical water stream 25 is between the criticaltemperature of water and 380 deg C. Maintaining the temperature ofsupercritical water stream 25 below the temperature of reactor effluent20 can reduce conversion reactions from occurring in supercriticalreactor 200.

Referring to FIG. 2, an embodiment of the upgrading process is providedwith reference to FIG. 1. Water stream 75 can be introduced to liquidpump 600. Water stream 75 can be any demineralized water having aconductivity less than 1.0 microSiemens per centimeter (μS/cm),alternately less 0.5 μS/cm, and alternately less than 0.1 μS/cm. In atleast one embodiment, water stream 75 is demineralized water having aconductivity less than 0.1 μS/cm. Water stream 75 can have a sodiumcontent of less than 5 micrograms per liter (μg/L) and alternately lessthan 1 μg/L. Water stream 75 can have a chloride content of less than 5μg/L and alternately less than 1 μg/L. Water stream 75 can have a silicacontent of less than 3 μg/L. In at least one embodiment, water stream 75can be at ambient temperature and pressure between 5 psig and 100 psig.In at least one embodiment, repeating the steps of pressurizing anddepressurizing between 5 psig and 100 psig can remove the dissolvedgases.

Liquid pump 600 can be any type of pump capable of increasing thepressure of water stream 75 to greater than the critical pressure ofwater. Examples of pumps suitable for use as liquid pump 600 can includemetering pumps, plunger pumps, or any other pumps known in the art. Thepressure of water stream 75 can be increased in liquid pump 600 toproduce pressurized water stream 85. The pressure of pressurized waterstream 85 can be greater than the critical pressure of water andalternately between 22.064 Megapascals (MPa) and 30 MPa. Pressurizedwater stream 85 can be introduced to water heater 650.

Water heater 650 can be any type of heat exchanger capable of increasingthe temperature of pressurized water stream 85 to greater than thecritical temperature of water. Examples of water heater 650 can includea heat exchanger, an electric heater, and a fired heater.

The temperature of pressurized water stream 85 can be increased in waterheater 650 to produce supercritical water stream 25.

Returning to FIG. 1, the ratio of the volumetric flow rate ofsupercritical water stream 25 to the combined volumetric flow rate ofheavy residue feed 10 and supercritical water feed 15 can be between 5:1and 1:10 at SATP and alternately between 1:1 and 1:4 at SATP.Maintaining a ratio of heavy residue feed 10 to supercritical water feed15 of less than 5:1 increases the efficiency of extraction in secondsupercritical reactor 200, as a ratio greater than 5:1 reduces theseparation efficiency and makes oil and water separation more difficult.Conversely, at a ratio of heavy residue feed 10 to supercritical waterfeed 15 of less than 1:10 can also reduce separation efficiency and makeoil and water separation more difficult.

Second supercritical reactor 200 can be any type of vertical vessel.Examples of reactors suitable for use in second supercritical reactor200 can include tubular-type, vessel-type, and combinations of the same.In at least one embodiment, second supercritical reactor 200 can be avessel-type reactor. Second supercritical reactor 200 can have a bodyand two heads, also referred to as ends. The body of secondsupercritical reactor 200 can be a cylindrical body. The heads ofsupercritical reactor 200 can be hemispherical-type, ellipisoidal-type,conical-type, or combinations of the same. In at least one embodiment,each head of second supercritical reactor 200 is the same type. In atleast one embodiment, each head of second supercritical reactor 200 is adifferent type.

Second supercritical reactor 200 can have a reactor volume such that theratio of total flow rate at SATP to reactor volume is between 1 per hourand 6 per hour and alternately between 1.25 per hour and 3.5 hour. Thetotal flow rate at SATP is the sum of the flow rate of heavy residuefeed 10, supercritical water feed 15, and supercritical water stream 25.The reactor volume of second supercritical reactor 200 is greater thanthe reactor volume of first supercritical reactor 100. The greatervolume in second supercritical reactor 200 facilitates separation of thelight components and the heavy components. Second supercritical reactor200 is in the absence of an external supply of catalyst. Secondsupercritical reactor 200 can be in the absence of an external supply ofhydrogen. Second supercritical reactor 200 is in the absence of addedcarbon, such as activated carbon. The pressure in second supercriticalreactor 200 is maintained between 22.064 MPa and 30 MPa. Secondsupercritical reactor 200 can act as an extractor for separating thelight components and heavy components in reactor effluent 20 withminimal conversion reactions occurring. A greater amount of conversionoccurs in first supercritical reactor 100 than second supercriticalreactor 200.

Second supercritical reactor 200 includes four ports, top inlet 205,bottom inlet 215, top outlet 210, and bottom outlet 220. The ports canbe any type of port capable of providing fluid flow to and from secondsupercritical reactor 200. Each port can be sized based on the flowconditions of the fluid stream that passes through that port.

In at least one embodiment, top inlet 205 and top outlet 210 can bepositioned in the top portion of second supercritical reactor 200, suchthat top inlet 205 is at a lower elevation relative to the position oftop outlet 210. The top portion is defined as the section of thecylindrical body of supercritical reactor 200 defining 10% of the totallength measured from the highest elevation of the cylindrical body ofsecond supercritical reactor 200. The highest elevation is the point onthe cylindrical body of reactor 200 that is the longest verticaldistance from grade. For example, if the total length of the cylindricalbody of second supercritical reactor 200 is 10 meters (m), the topportion is 1 m measured from the highest elevation of the cylindricalbody of second supercritical reactor 200. The top portion does notinclude the top head. Top inlet 205 can be positioned in the top portionof second supercritical reactor 200 below the top head. In at least oneembodiment, top inlet 205 can be positioned in the top portion of secondsupercritical reactor 200 and top outlet 210 can be positioned in thetop head of second supercritical reactor 200. In at least oneembodiment, top outlet 210 can be positioned at the highest elevation ofthe top head. The placement of top outlet 210 in the top head avoids theinlet stream of reactor effluent 20 from entering through top inlet 205and immediately exiting through top outlet 210. Placement of top outlet210 in the top head ensures reactor effluent 20 can interact withsupercritical water stream 25. Top outlet 210 is placed at a higherelevation than top inlet 205.

In at least one embodiment, bottom inlet 215 and bottom outlet 220 canbe positioned in the bottom portion of second supercritical reactor 200,such that bottom outlet 220 is at a lower elevation than bottom inlet215. The bottom portion is defined as the section of cylindrical body ofsupercritical reactor 200 defining 10% of the total length measured fromthe lowest elevation of the cylindrical body of second supercriticalreactor 200. The lowest elevation is the point on supercritical reactor200 that is the shortest vertical distance from grade. For example, ifthe total length of second supercritical reactor 200 is 10 m, the bottomportion is 1 m measured from the lowest elevation of the cylindricalbody of second supercritical reactor 200. The bottom portion does notinclude the bottom head. Bottom inlet 215 can be positioned in thebottom portion of second supercritical reactor 200 above the bottomhead. In at least one embodiment, bottom inlet 215 can be positioned inthe bottom portion of second supercritical reactor 200 and bottom outlet220 can be positioned in the bottom head of second supercritical reactor200. In at least one embodiment, bottom outlet 220 can be positioned atthe lowest elevation of the bottom head. The placement of bottom inlet215 at a higher elevation than bottom outlet 220 can avoid the bottomhead acting like a funnel and allows supercritical water stream 25 tointeract with the fluids in supercritical reactor 200 withoutimmediately exiting through bottom outlet 220. Bottom outlet 220 isplaced at a lower elevation than bottom inlet 215.

One of skill in the art will understand that placement of the nozzles onsecond supercritical reactor 200 can be determined based on size andspatial constraints.

Second supercritical reactor 200 has a temperature gradient with thegreatest temperatures at the top head proximate to top inlet 205 and thelowest temperatures at the bottom head proximate to bottom outlet 220.The maximum temperature in the top portion is the temperature of reactoreffluent 20. Second supercritical reactor 200 is not isothermal. Secondsupercritical reactor 200 can include a heater to maintain thetemperature. The heater can be an internal heater, an external heater,and combinations of the same. Examples of suitable heaters can includean electric heater, a fired heater, a heat exchanger and combinations ofthe same. Additionally, insulation and heat tracing elements can be usedto maintain the temperature gradient desired within second supercriticalreactor 200. The temperature in the bottom portion of secondsupercritical reactor 200 being less than the temperature of reactoreffluent 20 can reduce or eliminate the occurrence of conversionreactions occurring in the bottom portion with the heavy product.Advantageously, reducing or eliminating the occurrence of conversionreactions in second supercritical reactor 200 can minimize or preventthe production of coke and reduce potential for coking within secondsupercritical reactor 200. As a result, the conversion reactionsprimarily occur in first supercritical reactor 100. In at least oneembodiment, less than 5 wt % of the bottom of the barrel fractionundergoes conversion reactions in second supercritical reactor 200, andalternately less than 3 wt %.

In second supercritical reactor 200 the supercritical water fromsupercritical water stream 25 can push the light hydrocarbon fraction inthe bottom of the barrel fraction toward the top portion while thehydrocarbons in the bottom of the barrel fraction can settle toward thebottom portion. The hydrocarbons in the bottom of the barrel fractionare not easily miscible in supercritical water. However, the organiccompounds and light hydrocarbons in the light hydrocarbon fraction candissolve in the supercritical water from supercritical water stream 25,such that the supercritical water from supercritical water stream 25 canact as an extraction solvent for the light hydrocarbon fraction in thebottom of the barrel fraction. In at least one embodiment, secondsupercritical reactor 200 is a counter-current extraction type reactor.A counter-current extraction type reactor can maximize the extractioncapability of supercritical water. Second supercritical reactor 200contributes to the separation of the light hydrocarbon fraction from thebottom of the barrel fraction. Advantageously, supercritical water is asuitable solvent for use in extracting light hydrocarbons.Advantageously, energy efficiency is achieved by using and maintainingthe energy of reactor effluent stream 20 in second supercritical reactor200.

Upgraded product stream 30 can be withdrawn from top outlet 210 ofsecond supercritical reactor 200. The temperature of upgraded productstream 30 can be between 380 deg C. and 420 deg C. The pressure ofupgraded product stream 30 can be between 22.074 MPa and 30 MPa.Upgraded product stream 30 can include a light hydrocarbon fraction,water and combinations of the same. Upgraded product stream 30 cancontain greater than 50 wt % and alternately greater than 75 wt % of thecombined amount of water in supercritical water feed 15 andsupercritical water stream 25. Upgraded product stream 30 can containless than 10 wt % bottom of the barrel fraction, alternately less than 5wt % bottom of the barrel fraction, and alternately less than 1 wt %bottom of the barrel fraction. In at least one embodiment, upgradedproduct stream 30 contains a reduced amount of metals compared to heavyresidue stream 10. In at least one embodiment, upgraded product stream30 can contain less than 0.5 wt ppm vanadium. In at least one embodimentupgraded product stream 30 can contain less than 0.5 wt ppm nickel.Upgraded product stream 30 can be a bottom-free hydrocarbon stream.

Upgraded product stream 30 can be further processed to reduce thetemperature, reduce the pressure, and separate water from the lighthydrocarbon fraction. The water-free upgraded product can contain lessthan 0.3 wt % water.

Upgraded product stream 30 can be further processed and used for powergeneration. Further processing can include a hydroprocessing system,such as a hydrocracking process. Advantageously, using upgraded productstream 30 in a hydroprocessing system can extend catalyst life in thehydroprocessing system due to reduced amount of catalyst poisoning dueto reduced amounts of metals, such as vanadium, and formation of coke.Additionally, a hydroprocessing system using upgraded product stream 30as the feed can be operated at reduced temperatures, greater spacevelocity, and reduced hydrogen pressure compared to introducing a heavyresidue directly to a hydroprocessing system. Upgraded product stream 30can be used as a feed stream for power generation in a gas turbinebecause of the trace amounts of vanadium. Advantageously, using upgradedproduct stream 30 in a gasification process to produce hydrogen reducesplugging in the gasification process as compared to the bottom fractionfrom a conventional supercritical water process. In at least oneembodiment, upgraded product stream 30 is used in a gasificationprocess.

Heavy product stream 40 can be withdrawn from bottom outlet 220 ofsecond supercritical reactor 200. The temperature of heavy productstream 40 can be between 380 deg C and 420 deg C. The pressure of heavyproduct stream 40 can be between 22 MPa and 30 MPa. In at least oneembodiment, a temperature sensor can be placed proximate to bottomoutlet 220. The temperature sensor can provide data on the temperatureof heavy product stream 40 as part of a control loop to tune thetemperature in second supercritical reactor 200. Heavy product stream 40can include bottom of the barrel fraction, solid particles, cokeprecursors, water, and combinations of the same. In at least oneembodiment, heavy product stream 40 can contain more aromatichydrocarbons than non-aromatic hydrocarbons. Heavy product stream 40 cancontain the water not present in upgraded product stream 30, includingless than 50 wt % and alternately less than 25 wt % of the combinedamount of water in supercritical water feed 15 and supercritical waterstream 25.

Heavy product stream 40 can be further processed to reduce thetemperature, reduce the pressure, and separate water from the bottom ofthe barrel fraction. The separated heavy hydrocarbons can be used toproduce asphalt or solid coke.

The pressure in the system can be maintained from the pumps through thereactors by a depressurizing device downstream of second supercriticalreactor 200. In at least one embodiment, upgraded product stream 30 caninclude a depressurizing device to control pressure in the system. In atleast one embodiment, a pressure control device can be positionedbetween first supercritical reactor 100 and second supercritical reactor200. In at least one embodiment, heavy product stream 40 can include oneor more valves to control flow rate and reduce the pressure of heavyproduct stream 40.

Both the first supercritical reactor and second supercritical reactor ofthe process to upgrade the bottom of the barrel fraction are in theabsence of a flash drum. The process to upgrade the bottom of the barrelfraction is in the absence of a mixer between the first supercriticalreactor and the second supercritical reactor.

EXAMPLES

Examples. The Example was a simulated process using Aspen-HYSYS based onexperimental data of a system described with reference to FIG. 2.

Residue feed 50 was introduced to hydrocarbon pump 300 at a flow rate of650 kg/h and a liquid volume flowrate of 100 barrels per day(barrel/day). The pressure of residue feed 50 was increased in waterpump 300 to produce pressurized residue feed 60. Pressurized residuefeed 60 was at a pressure of 25 MPa. The temperature of pressurizedresidue feed 60 was increased in hydrocarbon exchanger 350 to produceheavy residue feed 10. Heavy residue feed 10 was at a temperature of 200deg C. Heavy residue feed 10 was introduced to mixer 500.

Water feed 55 was introduced to water pump 400 at a flow rate of 661kg/h and a liquid volume flowrate of 100 barrel/day. The pressure ofwater feed 55 was increased in water pump 400 to produce pressurizedwater feed 65. Pressurized water feed 65 was at a pressure of 25 MPa.The temperature of pressurized water feed 65 was increased in waterexchanger 450 to produce supercritical water feed 15. Supercriticalwater feed 15 was at a temperature of 450 deg C. Supercritical waterfeed 15 was introduced to mixer 50.

Water stream 75 was introduced to fluid pump 600 at a flow rate of 331kg/hr and a liquid volume flowrate of 50 barrel/day. The pressure ofwater stream 75 was increased in fluid pump 600 to produce pressurizedwater stream 85. Pressurized water stream 85 was at a pressure of 25MPa. The temperature of pressurized water stream 85 was increased inwater heater 650 to produce supercritical water stream 25. Supercriticalwater stream 25 was at a temperature of 400 deg C.

Heavy residue feed 10 and supercritical water feed 15 were mixed inmixer 50 to produce mixed feed 70. Mixed feed 70 was introduced to firstsupercritical reactor 100. Reactor effluent 20 was withdrawn from firstsupercritical reactor 100. Reactor effluent 20 was introduced to topinlet 205 of second supercritical reactor 200. Supercritical waterstream 25 was introduced to bottom inlet 210 of second supercriticalreactor 200. Upgraded product stream 30 was withdrawn from top outlet215. Heavy product stream 40 was withdrawn from bottom outlet 220. Thestream conditions are shown in Table 1.

TABLE 1 Stream Conditions Stream Name 20 30 40 Temperature (deg C.) 420410 410 Pressure (MPa) 25 25 25 Mass Flow (kg/h) 1311 1291 20

In the experimental runs, reactor effluent 20, upgraded product stream30, and heavy product stream 40 were sampled and then subjected toseparation methods to separate oil, water, and gases from the streams.The separation methods were performed according to ASTM 4007. The massflow of liquid hydrocarbons was calculated for each stream and theresults are contained in Table 2.

TABLE 2 Stream Compositions Name Residue Feed Reactor Upgraded HeavyProduct 50 Effluent 20 Product 30 Stream 40 Specific Gravity (API) 12.717.5 21.1 10.5 Distillation  5% 361 297 289 524 (TBP, deg C.) 10% 390337 332 552 30% 468 420 406 607 50% 524 464 441 621 70% 579 519 496 63490% 656 592 552 681 Sulfur Content (wt %) 3.7 2.5 1.8 4.5 ConradsonCarbon Content (wt %) 11.3 2.9 0.3 8.2 Kinematic Viscosity @ 121 F.(cSt) 760 32 4 * Vanadium Content (wt ppm) 41 7 <0.1 24.3 Mass Flow(kg/hr) 650 637 550 78 *The kinematic viscosity of heavy product 40 wasnot measurable because it was greater than the measurable range.

An upgrading process with only one supercritical reactor results in aproduct stream having about 35 wt % bottom of the barrel. By contrast,the process described here, which includes two supercritical reactors,where the second reactor operates in a cross-flow design results in anupgraded product stream that contains less than 5 wt % bottom of thebarrel. An upgraded product stream with less than 5 wt % bottom of thebarrel is suitable for use in gasification systems, power generationsystems, and conventional hydroprocessing.

Although the present invention has been described in detail, it shouldbe understood that various changes, substitutions, and alterations canbe made hereupon without departing from the principle and scope of theinvention. Accordingly, the scope of the present invention should bedetermined by the following claims and their appropriate legalequivalents.

There various elements described can be used in combination with allother elements described here unless otherwise indicated.

The singular forms “a”, “an” and “the” include plural referents, unlessthe context clearly dictates otherwise.

Optional or optionally means that the subsequently described event orcircumstances may or may not occur. The description includes instanceswhere the event or circumstance occurs and instances where it does notoccur.

Ranges may be expressed here as from about one particular value to aboutanother particular value and are inclusive unless otherwise indicated.When such a range is expressed, it is to be understood that anotherembodiment is from the one particular value to the other particularvalue, along with all combinations within said range.

Throughout this application, where patents or publications arereferenced, the disclosures of these references in their entireties areintended to be incorporated by reference into this application, in orderto more fully describe the state of the art to which the inventionpertains, except when these references contradict the statements madehere.

As used here and in the appended claims, the words “comprise,” “has,”and “include” and all grammatical variations thereof are each intendedto have an open, non-limiting meaning that does not exclude additionalelements or steps.

That which is claimed is:
 1. A system to produce a light hydrocarbonfraction from a heavy residue feed, the system comprising: a firstsupercritical reactor, the first supercritical reactor configured tooperate such that the heavy residue feed and a supercritical water feedundergo conversion reactions to produce a reactor effluent, wherein thetemperature in the first supercritical reactor is between 380 deg C. and450 deg C., wherein the pressure in the first supercritical reactor isgreater than the critical pressure of water, wherein the reactoreffluent comprises a light hydrocarbon fraction, a bottom of the barrelfraction, and water; a top inlet in a top portion of a secondsupercritical reactor fluidly connected to the first supercriticalreactor, the top inlet configured to receive the reactor effluent,wherein the second supercritical reactor comprises a vertical reactor; abottom inlet in a bottom portion of the second supercritical reactor,the bottom inlet configured to receive a supercritical water stream,wherein the supercritical water stream comprises supercritical water,wherein the temperature of the supercritical water stream is between thecritical temperature of water and 10 deg C. less than the temperature ofreactor effluent; the second supercritical reactor configured to operatesuch that the bottom of the barrel fraction is configured to settle inthe bottom portion of the second supercritical reactor, wherein thesupercritical water in the supercritical water stream is operable toextract the light hydrocarbon fraction from the reactor effluent; a topoutlet fluidly connected to the top portion of the second supercriticalreactor, the top outlet configured to receive an upgraded productstream, wherein the upgraded product stream comprises the lighthydrocarbon fraction, wherein the top outlet is positioned at a higherelevation than the top inlet; and a bottom outlet in the bottom portionof the second supercritical reactor, the bottom outlet configured toreceive a heavy product stream, wherein the heavy product streamcomprises the bottom of the barrel fraction, wherein the bottom outletis positioned at a lower elevation than the bottom inlet.
 2. The systemof claim 1, further comprising: a hydrocarbon pump, the hydrocarbon pumpconfigured to increase a pressure of a residue feed to produce apressurized residue feed, wherein the pressure of the pressurizedresidue feed is greater than the critical pressure of water; ahydrocarbon exchanger fluidly connected to the hydrocarbon pump, thehydrocarbon exchanger configured to increase a temperature of thepressurized residue feed in the hydrocarbon exchanger to produce theheavy residue feed; a water pump, the water pump configured to increasea pressure of a water feed to produce a pressurized water feed, whereinthe pressure of the pressurized water feed is greater than the criticalpressure of water; a water exchanger fluidly connected to the waterpump, the water exchanger configured to increase a temperature of thepressurized water feed in the water exchanger to produce thesupercritical water feed; a liquid pump, the liquid pump configured toincrease a pressure of a water stream to produce a pressurized waterstream, wherein the pressure of the pressurized water stream is greaterthan the critical pressure of water; and a water heater fluidlyconnected to the liquid pump, the water heater configured to increase atemperature of the pressurized water stream to produce the supercriticalwater stream.
 3. The system of claim 2, further comprising the steps of:a mixer fluidly connected to the hydrocarbon exchanger and the waterexchanger, the mixer configured to mix the heavy residue feed and thesupercritical water feed to produce a mixed feed, wherein a ratio of thevolumetric flow rate of the supercritical water feed to the volumetricflow rate of the heavy residue feed is between 10:1 and 1:4 at standardambient temperature and pressure (SATP).
 4. The system of claim 1,wherein the upgraded product stream comprises less than 10 wt % bottomof the barrel fraction.
 5. The system of claim 1, wherein a ratio of thevolumetric flow rate of the supercritical water stream to the combinedvolumetric flow rate of heavy residue feed and supercritical water feedis between 5:1 and 1:10 at standard atmospheric temperature and pressure(SATP).
 6. The system of claim 1, wherein a residence time in the firstsupercritical reactor is between 1.2 minutes and 60 minutes.
 7. Thesystem of claim 1, wherein a ratio of a total flow rate at SATP insecond supercritical reactor to a reactor volume of second supercriticalreactor is between 1 per hour and 6 per hour.
 8. The system of claim 1,wherein the heavy residue feed is selected from the group consisting ofan atmospheric residue, a vacuum gas oil, and a vacuum residue.
 9. Thesystem of claim 1, wherein the bottom portion comprises the section of acylindrical body of the supercritical reactor defining 10% of the totallength measured from a lowest elevation of the cylindrical body of thesecond supercritical reactor.
 10. The system of claim 1, wherein the topportion comprises the section of a cylindrical body of the supercriticalreactor defining 10% of the total length measured from a highestelevation of the cylindrical body of the second supercritical reactor.